Core/Collision: Models with flag MOD_M2 (mostly trees, among some other objects) should not be taken into account for LoS checks, this check does not apply to gameobjects (yet)

closes #3495

Signed-off-by: Subv <s.v.h21@hotmail.com>

src/server/collision/Management/VMapManager2.cpp

@@ -245,7 +245,7 @@ namespace VMAP
         return false;
     }
 
-    WorldModel* VMapManager2::acquireModelInstance(const std::string& basepath, const std::string& filename)
+    WorldModel* VMapManager2::acquireModelInstance(const std::string& basepath, const std::string& filename, uint32 flags/* Only used when creating the model */)
     {
         //! Critical section, thread safe access to iLoadedModelFiles
         TRINITY_GUARD(ACE_Thread_Mutex, LoadedModelFilesLock);
@@ -261,6 +261,7 @@ namespace VMAP
                 return NULL;
             }
             sLog->outDebug(LOG_FILTER_MAPS, "VMapManager2: loading file '%s%s'", basepath.c_str(), filename.c_str());
+            worldmodel->Flags = flags;
             model = iLoadedModelFiles.insert(std::pair<std::string, ManagedModel>(filename, ManagedModel())).first;
             model->second.setModel(worldmodel);
         }